Neotypification of the Interspecific Hybrid 3rehderiana () Originating at the Arnold Arboretum

Jared Rubinstein and Michael Dosmann Arnold Arboretum of Harvard University, 125 Arborway, Jamaica Plain, Massachusetts 02130, U.S.A. Author for correspondence: [email protected]

ABSTRACT. The interspecific hybrid Pterocarya 3 that there is no published record of a type specimen rehderiana C. K. Schneid. was first described in designation for P. 3rehderiana. Schneider did not 1903 but there is no record of typification. A neotype is include a type designation in his 1904 description, designated here from among the earliest collections of nor did a literature search reveal any other publication the nothospecies stored at the Herbarium of the Arnold after the fact. We reviewed the P. 3rehderiana spec- Arboretum (A). imens at the Harvard University Herbaria (including the Key words: Alfred Rehder, Camillo Schneider, Arnold Arboretum herbarium) from Rehder’sand Juglandaceae. Schneider’s era and did not find any annotations or notes indicating that any of the specimens were ever Pterocarya 3rehderiana C. K. Schneid. is a notho- considered the type. Similarly, personal correspon- species originating from an interspecific cross between dence with the herbarium staffs at the Royal Botanic P. stenoptera C. DC. and P. fraxinifolia (Lam.) Spach Gardens, Kew (Liz Brogan at K, pers. comm.), the Royal that displays intermediate characteristics between its Botanic Garden Edinburgh (Hannah Atkins at E, two parents (Schneider, 1906). The hybrid also grows pers. comm.), the Botanischer Garten und Botanisches more vigorously than its parents and appears to be more Museum in Berlin (Robert Vogt at B, pers. comm.), cold hardy (Rehder, 1947). Given the geographically the Naturhistorisches Museum in Vienna (Christian distinct native ranges of the two parent species (P. Br¨auchler at W, pers. comm.), and the Mus´eum National stenoptera grows in East , while P. fraxinifolia is d’Histoire Naturelle in Paris (C´ecile Aupic at PC, pers. native to the Caucasus), modern hybridization has likely comm.) did not provide any further evidence of any only occurred under cultivation. specimen with annotations indicating it was a type The first recorded observation of Pterocarya 3 specimen. It is possible that Schneider deposited a rehderiana occurred at the Arnold Arboretum in specimen of the nothospecies locally, at the predecessor 1903 in Boston, Massachusetts, when Alfred Rehder of the Naturhistorisches Museum in Vienna where he noted that labeled as P. stenoptera (Arnold Arbo- apparently lived at the time, which would have been retum accessions 1191 and 16787) displayed char- subsequently destroyed in July of 1945 (Stern, 1978; acteristics of both P. stenoptera and P. fraxinifolia Br¨auchler, pers. comm.). (Rehder, 1903). The trees in question were grown from Therefore, because a type specimen was never pub- collected from a P. stenoptera at the Arboretum lished, and no existing specimen includes any annota- de Segrez outside of Paris by Pierre Alphonse Lavall´ee tions indicating that it was considered a type by and sent to the Arnold Arboretum in 1879 and 1880 Schneider, an existing specimen in the Herbarium of (Rehder, 1913). Rehder identified the trees as hybrids the Arnold Arboretum collected in 1901 is designated in 1903 (though without a proposed hybrid epithet), then here as the neotype for Pterocarya 3rehderiana. apparently conferred with his friend and colleague Camillo Pterocarya 3rehderiana K. Schneider in Vienna (Rehder, 1903). In 1904, Schneider C. K. Schneid., Ill. Handb. published a description with a new epithet in the first Laubholzk 1: 93. 1904. TYPE: U.S.A. Massachusetts: volume of his Illustriertes Handbuch der Laubholzkunde Jamaica Plain, 1901, J. G. Jack s.n. (neotype, desig- based on material from the “Bastardes” growing in nated here, A [barcode] 00786582!). Figure 1. the Arnold Arboretum and sent to him by Rehder Notes. The selected specimen was collected by (Schneider, 1906). John G. Jack in 1901 from a multi- accession In 2018, during a curatorial review of the Arnold (accession number 1191) growing in the Arnold Arbo- Arboretum’s Juglandaceae collection in preparation for retum’s Living Collection; however, the label does not the possible arrival of thousand cankers disease, a indicate which exact tree within accession 1191 Jack fungal/insect complex that affects L. and Ptero- vouchered. The specimen shows the key characteristics carya Kunth in North America, the authors observed of the hybrid that differentiate it from its parents, namely

VERSION OF RECORD FIRST PUBLISHED ONLINE ON 29 OCTOBER 2020 AHEAD OF WINTER 2020 ISSUE. doi: 10.3417/2020580 NOVON 28: 232–234. Volume 28, Number 4 Rubinstein & Dosmann 233 2020 Neotypification of Pterocarya 3rehderiana (Juglandaceae)

Figure 1. Neotype of Pterocarya 3rehderiana C. K. Schneid. High-resolution scanned image taken at the Herbarium of the Arnold Arboretum (A, 2019). 234 Novon

the narrowly winged rachis; narrow, acuminate, and Literature Cited coarsely serrate leaflets; and narrow, long wings in the 3 fruit (Rehder, 1913). There are currently four living Rehder, A. 1903. stenoptera (hybr. nov.). Mitt. Deutsch. Dendrol. Ges. 12: 116–117. trees in accession 1191. In 1913, Rehder estimated Rehder, A. 1913. Pterocarya rehderiana C. K. Schneid. Pp. the height of one of them at about 12 m; the tallest 79–81 in C. S. Sargent (editor), Trees and Shrubs, vol. 2. today is almost 25 m. One particularly striking spec- Houghton, Mifflin and Company, Boston. imen (1191*E) has two massive leaders with DBHs Rehder, A. 1947. Manual of Cultivated Trees and Shrubs of 103 and 102.5 cm, respectively. Hardy in North America, Exclusive of the Subtropical and Warmer Temperate Regions, 2nd ed. Macmillan, Acknowledgments. The authors thank Anthony New York. Schneider, C. K. 1906. Illustriertes Handbuch der Laubholzkund, Brach and Kanchi Gandhi at the Harvard University vol.I.GustavFisher,Jena. Herbaria, as well as the curatorial staffs at B, E, K, and Stern, L. S. 1978. Index Xylariorum. Institutional col- PC, for their assistance with this project. lections of the world. Taxon 27: 233–269.

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